Novel spiro-based hole transporting materials for efficient perovskite solar cells.

Three spiro-acridine-fluorene based hole transporting materials (HTMs), namely CW3, CW4 and CW5, are employed in the fabrication of organic-inorganic hybrid perovskite solar cells. The corresponding mesoscopic TiO2/CH3NH3PbI3/HTM devices are investigated and compared with that made with commercial spiro-OMeTAD. The best conversion efficiency of 16.56% is achieved for CW4 in the presence of tBp and Li-TFSI as additives and without a cobalt dopant. The performances of CW4 are further examined in terms of conductivity, mobility, morphology, and stability to show its potential as an alternative HTM.